The long-term goal of this project is to design and produce, by using combinations of molecular biology, computational molecular modeling, and protein biochemistry, an array of genetically engineered streptavidins with enhanced properties applicable to the development of new diagnostic and therapeutic technologies and biomedical assays. Phase I of this project will focus on molecular technologies that allow efficient, ordered immobilization of recombinant streptavidins on solid surfaces. Streptavidin, a protein which has an extremely tight binding affinity for a vitamin, biotin, is one of the most frequently used proteins in diagnostic tests and biological assays. For the last several years, the investigators at Boston University of this project have designed and produced wide variety of recombinant streptavidins that have enhanced properties over the natural protein. Phase I of this project will alter, by genetic engineering, the structures of several selected recombinant streptavidins to make them immobilizable on solid surfaces in an efficient manner. This will allow the use of the enhanced properties of these recombinant streptavidins in current solid-phase diagnostic tests and biomedical assays, with the great possibility of providing them with improved performance, greater versatility, and reduced costs. PROPOSED COMMERCIAL APPLICATION: Many currently used diagnostic and biochemical tests are solid-phase assays. In a number of solid-phase assay systems, streptavidin is often immobilized covalently on solid surfaces so that biotinylated capturing reagents, such as antibodies, and biotinylated probes, such as oligonucleotides complementary to target sequences, can be attached stably on the solid surface. Phase I of this project aims to alter, by genetic engineering, the structures of several selected recombinant streptavidins to make them immobilizable on solid surfaces in an efficient manner. The resulting streptavidin variants will be incorporated into existing solid- phase assay products to enhance their performance. They will also allow the development of new solid-phase assay products.